At least a million mainly elderly people in Britain have a heart condition called atrial fibrillation (AF), in which the chambers do not beat in synch, causing blood to pool inside and clot.

These clots can get washed out of the heart and become lodged in neck or brain blood vessels, causing a devastating stroke.

Having AF increases the chance of stroke fivefold, according to the Stroke Association, and those it causes tend to be more debilitating than normal.

Most people diagnosed with AF are currently prescribed warfarin, a blood thinner used since the 1950s that was originally developed as rat poison.

Warfarin cuts the risk of stroke by two-thirds, but patients have to undergo regular blood tests to ensure the dosage is correct. Too much warfarin can cause excessive bleeding. Drinking alcohol, eating broccoli and taking other medicines can also affect its action.

These problems mean doctors are sometimes reluctant to prescribe warfarin.

Now the National Institute for Health and Clinical Excellence (Nice) has recommended that doctors in England and Wales should be able to prescribe a new drug called apixaban, marketed under the brand name Eliquis. Although only draft guidance, it is unlikely Nice will receive objections.

The decision comes 18 months after a large study found the twice-daily pill to be even more effective at preventing stroke than warfarin, while reducing the number of bleeds.

Compared to warfarin, it cut the number of strokes by 21 per cent and the number of major bleeds including brain haemorrhage by 31 per cent. Deaths from all causes were 11 per cent lower.

Compared to taking nothing, it is likely that apixaban cuts the odds of stroke by about 80 per cent.

Apixaban is the third ‘new generation’ stroke-prevention drug recommended by Nice recently. The other two, rivaroxaban and dabigatran, are similarly effective. All cost a little over £2 a day, compared to about £1 a day for warfarin.

Professor Carole Longson, from Nice, said its appraisal committee had heard from patient experts “that warfarin can have a greater impact on a person’s quality of life than AF itself.”

She said the three new drugs had “potential benefits” for people with AF because they did not require regular monitoring and dose adjustments.

Dr Peter Coleman, deputy director of research at the Stroke Association, said: “We welcome the approval of apixaban and are pleased that health professionals will now have an extra treatment in their armoury when treating patients with atrial fibrillation in order to reduce their risk of stroke.”